By dpa correspondents
Washington - The recent release of emails supposedly belonging to Hunter Biden, son of US presidential candidate Joe Biden, has "all the classic earmarks of a Russian information operation," 50 former senior intelligence officials said in a letter published on Monday.
The New York Post last week reported on a batch of emails it obtained from a laptop supposedly left by Hunter Biden at a repair shop, suggesting that Joe Biden had used his former position as vice president to enrich his son.
Other news organizations have questioned the authenticity of the laptop's contents, which were provided to the Post by President Donald Trump's ally and lawyer Rudy Giuliani.
Giuliani has previously spread false information about a discredited theory that accuses the former vice president of pressuring Ukraine to fire its top prosecutor to benefit a Ukrainian natural gas company that employed Hunter Biden.
Joe Biden has denied all wrongdoing, saying that he did not speak to his son about his business.
In Monday's letter, published by news website Politico, ex-intelligence officials including several ex-CIA directors said there were a "number of factors that make us suspicious of Russian involvement."
It would be "consistent with Russian objectives" to create "political chaos" in the US, as well as to "undermine the candidacy" of Joe Biden and help Trump, the former officials wrote.
"For the Russians at this point, with Trump down in the polls, there is incentive for Moscow to pull out the stops," they continued.
"We want to emphasize that we do not know if the emails ... are genuine or not and that we do not have evidence of Russian involvement - just that our experience makes us deeply suspicious that the Russian government played a significant role in this case," they said.
Signatories to the letter included ex-CIA directors Leon Panetta, John Brennan and Mike Hayden, as well as former acting directors John McLaughlin and Michael Morell and ex-director of national intelligence Jim Clapper.
When the Post first published the story last week, Twitter blocked users from sharing or linking to it amid concerns that it could be linked to a disinformation campaign weeks ahead of the presidential election, while Facebook said it would reduce distribution of the article pending a review by a fact-checker.
Trump, along with prominent conservatives, attacked Twitter for the move, accusing the company of attempting to shield the Democratic presidential nominee.
Twitter later appeared to clarify their policy going forward by saying they will no longer block hacked material unless it is directly released by the hacker, according to Vijaya Gadde, Twitter's legal, policy and trust and safety lead.
Gadde also said the company would label tweets to provide context, instead of blocking links from being shared on Twitter.
Foreign election interference has been a topic of interest in Washington in the lead up to the November elections.
Earlier this month, US National Security Adviser Robert O'Brien said he had received assurance from Russia that it would not interfere in the upcoming polls, after National Counterintelligence and Security Center director Bill Evanina said in August that Moscow is taking a range of measures "primarily to denigrate former Vice President Biden."
The US intelligence community assessed that Russia interfered in the 2016 US presidential election on behalf of Trump, and a Senate Intelligence Committee report released last month came to the same conclusion.